KR101472229B1 - Grain oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

A directional electric steel sheet capable of reducing iron loss even when it is stacked on a transformer iron core or the like is provided by the magnetic domain refining treatment. In the directional electric steel sheet in which thermal deformation is introduced in a matrix in which strain points are arranged in a direction intersecting the rolling direction of the steel sheet, the size of the deformation area introduced from the above-mentioned matrix is 0.10 mm or more and 0.50 mm or less, 0.10 mm or more and 0.60 mm or less.

Description

TECHNICAL FIELD [0001] The present invention relates to a grain-oriented electrical steel sheet and a method of manufacturing the same. BACKGROUND OF THE INVENTION [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional electric steel sheet suitable for an iron core material such as a transformer and a manufacturing method thereof.

The grain-oriented electrical steel sheet is mainly used as an iron core of a transformer and is required to have excellent magnetization characteristics, particularly low iron loss. For this purpose, it is important to highly arrange the secondary recrystallized steel sheet in the (110) [001] orientation (so-called Goss orientation) and to reduce the impurities in the steel sheet. Control of the crystal orientation and reduction of impurities are limited in terms of balance with manufacturing cost and the like. Therefore, a technique of introducing non-uniformity to the surface of the steel sheet by physical methods to reduce the iron loss by subdividing the width of the magnetic domain, that is, technology of domain segmentation has been developed.

For example, Patent Document 1 proposes a technique of reducing the iron loss of a steel sheet by irradiating a laser beam onto a final product plate, introducing a high-density region into the surface layer of the steel sheet, and narrowing the magnetic domain width. Patent Document 2 proposes a technique of controlling the width of a magnetic domain by irradiation of an electron beam.

Japanese Patent Publication No. 57-2252 Japanese Patent Publication No. 6-72266

However, in the case of applying the grain-oriented electrical steel sheet obtained by subjecting the above-described laser or electron beam to sub-refinement and making the low iron loss to the actual transformer, the iron loss of the actual machine transformer is not improved even if the iron loss of the material , That is, the building factor BF is poor.

Therefore, the object of the present invention is to provide a grain-oriented electrical steel sheet that can reduce iron loss even when it is stacked on an iron core or the like of a transformer, by the domain refining treatment.

However, in order to lower the iron loss of the grain-oriented electrical steel sheet when the grain-oriented electrical steel sheet is used as the iron core of the transformer, in other words, it is necessary not only to lower the iron loss in the rolling direction but also to lower the iron loss in the rolling direction.

As to the magnetization state in the transformer of the excitation, it is known that, when excited in parallel in the rolling direction, so-called magnetization rotation occurs in which magnetization is directed in a direction other than the rolling direction. For example, when a transformer of a three-phase triangular sector core is excited at a magnetic flux density of 1.7 T in parallel in the rolling direction, it is confirmed in the inventors' investigation that the magnetic flux of 0.1 to 1.0 T is locally directed in the direction perpendicular to the rolling direction . In the grain-oriented electrical steel sheet, when the magnetization is directed to other than the rolling direction, the magnetization is directed in a direction with a low magnetic permeability, so that the iron loss is increased. This increase in iron loss due to magnetization rotation causes the iron loss of the transformer to be larger than the iron loss (iron loss in the rolling direction) of the material itself.

The value obtained by dividing the iron loss in the transformer by the iron loss of the material under the same magnetizing condition is called BF (building factor) as an index showing the deterioration of the magnetic characteristics in this transformer. To reduce the BF, It is important to reduce the iron loss other than the rolling direction, particularly the iron loss in the direction perpendicular to the rolling direction.

Therefore, as a result of thermally introducing a deformation area of an appropriate size into a row on an ascending line where the adjacent deformation areas are spaced apart at appropriate intervals, the iron loss in both the rolling direction and the direction perpendicular to the rolling direction is small, It was found that a grain-oriented electrical steel sheet having a small iron loss was obtained.

Here, the principle of lowering the iron loss by introducing deformation is as follows. That is, when deformation is introduced, a tensile force is applied in the direction of the spline, and a reflux magnetic field is generated from the deformation as a starting point. As a result of the generation of the reflux zone, the static magnetic energy of the steel sheet is increased, while the 180 degree magnetic domain is subdivided so that the iron loss is reduced. As a result, the iron loss in the rolling direction is reduced. In other words, when the amount of deformation increases and a large amount of reflux occurs, the 180 degree magnetic domain is further refined and the iron loss in the rolling direction is reduced. Further, the increase of the tensile force in the direction of the splitting increases the magnetic permeability in the direction perpendicular to the rolling direction by the antistatic effect, and as a result, the iron loss in the direction perpendicular to the rolling direction is also reduced. However, the iron loss in the rolling direction is increased because the eddy current loss is reduced due to the reduction of the magnetic domain width, but the hysteresis loss is increased when the deformation amount is increased to a proper amount or more. Further, when the density of the deformation region in the steel sheet is high, the flow of magnetization is hindered, so that the hysteresis loss in the rolling direction and the direction perpendicular to the rolling direction is increased.

From the above, it is possible to reduce both the iron loss in the rolling direction and the iron loss in the direction perpendicular to the rolling direction, and it is possible to produce a grain-oriented electrical steel sheet having a small transformer iron loss if an appropriate amount of deformation can be imparted to the steel sheet with an appropriate deformation area density.

Next, the electron beam was irradiated under various irradiation conditions to investigate proper deformation introduction conditions, and the size of the introduced deformation area and the interval between adjacent deformation areas in each steel sheet were examined. The measurement of the size of the deformation area and the mutual spacing will be described later. In addition, we investigated the rolling direction of W _17/50, rolling perpendicular direction W _2/50 change in the irradiation of the front and rear. The excitation in the direction perpendicular to the rolling direction was determined as an index when the average value of the rolling quadrature components of the magnetic flux density in the transformer examined by the inventors was 0.2 T.

In the experiment, electron beams having an acceleration voltage of 40 kV and a beam current value of 2.5 mA were continuously irradiated in a direction orthogonal to the rolling direction, Respectively. The continuous irradiation was performed at a beam scanning speed of 4 m / s, and the interval between irradiation points was scanned at a beam scanning speed of 50 m / s. The test piece was a 0.23 mm thick directional electric steel plate, and a plate having B ₈ of 1.93 T before irradiation was used.

The size of the deformation area, the distance between adjacent deformation areas, and the measurement method are as follows.

[Size of deformation area]

After the surface coating of the steel sheet subjected to the final annealing treatment is removed with an acid or an alkali, the hardness of the strain-inducing portion is measured by a nanoindenter. A portion having a hardness at least 10% higher than its hardness is defined as a deformation introduction region (deformation region introduced into the matrix) based on the hardness at a position spaced by 1 mm or more from the deformation.

The maximum length in the direction perpendicular to the rolling direction in the deformation introduction area is defined as the size of the deformation area. However, the maximum length in the rolling direction is defined as the size of the deformation area under the continuous irradiation condition or the condition in which the deformation areas of the adjacent interstices overlap each other. Based on the above definition, the size of the deformation area is measured. More specifically, the deformation points at the central portion of the plate are measured at 10 points from the row of three rows for one sample, and the average value is determined.

[Spacing of adjacent deformation areas]

The shortest length of the portion without deformation influence between the adjacent deformation areas is defined as the interval between the adjacent deformation areas. In a condition in which continuous irradiation conditions or deformation areas overlap, the interval between adjacent deformation areas is defined as 0 mm. Based on the above definition, the interval between adjacent deformation areas is measured. More specifically, the deformation points at the central portion of the plate are measured at 10 points from the row of three rows for one sample, and the average value is determined.

First, Table 1 shows the results of examining the size of the introduced deformation area and the spacing between adjacent deformation areas in respective steel sheets when the irradiation conditions and the irradiation spot intervals in the direction perpendicular to the rolling direction were changed variously . Further, in Figures 1 and 2, it shows the change in the adjacent to the distance between the modified region, the rolling direction of ₁₇ W _{/ 50,} rolling perpendicular direction of ₂ W _{/ 50} to.

1, the distance between the adjacent two of the deformation zone to not more than 0.60 ㎜, the rolling direction W _17/50 is small. It is considered that the narrower the interval between the adjacent deformation areas, the larger the amount of deformation introduced, the greater the refinement effect of the magnetic domain, and the lower the iron loss.

On the other hand, as shown in Fig. 2, for performing at least the adjacent distance between the modified region to 0.10 ㎜ conditions jeomryeol irradiation, the more perpendicular to the rolling core loss W _2/50 in a direction decreasing by more than 10% when examined in a row. This is considered to be because the increase of the hysteresis loss in the direction perpendicular to the rolling direction can be suppressed by minimizing the deformation introduction area.

Next, the influence of the size of the deformation area was investigated. Accelerating voltage: 40 kV electron beams are alternately arranged at intervals of 7 mm in the direction perpendicular to the rolling direction of the steel sheet and at intervals of 0.2 mm or more and 0.3 mm or less in the adjacent deformation areas, The beam diameter and the current density were adjusted so that the size varied, and the electron beam irradiation was performed in an array. Figure 3, as shown the relationship between the iron loss and the size of the deformation zone, when the 0.5 ㎜ or less than 0.1 ㎜ size of the deformation zone, in the rolling direction W _17/50 is small. This is because, as the size of the deformation region is larger, the amount of deformation is increased and the effect of the domain refining is exhibited to reduce the iron loss. However, when the deformation region becomes larger and a deformation exceeding a certain level is introduced, the hysteresis loss in the rolling direction becomes larger, do. Yi as shown in FIG. 4, the iron loss of a size above 0.1 ㎜ rolled perpendicular direction of the deformation area W _2/50 is reduced. It is considered that this is because, when the size of the deformation area is less than 0.1 mm, reflux bulge which lowers the iron loss in the direction perpendicular to the rolling direction is not sufficiently generated.

From the above experimental results, it can be seen that the introduction of deformation into the matrix in which the size of the deformation area and the spacing between the adjacent deformation areas are appropriate makes the iron loss in both the rolling direction and the direction perpendicular to the rolling small, It has come to find out that it becomes a small directional electric steel sheet.

That is, the structure of the present invention is as follows.

1. A grain-oriented electrical steel sheet in which thermal strain is introduced in a matrix in which strain points are arranged in a direction intersecting the rolling direction of a steel sheet, wherein a size of the strain area introduced in the above- A directional electric steel sheet having an interval of 0.10 mm or more and 0.60 mm or less.

2. The grain-oriented electrical steel sheet according to 1 above, wherein the row interval in the rolling direction of the matrix is 2 to 10 mm.

3. When thermal deformation is introduced by electron beam irradiation in a matrix of deflection points arranged in a direction intersecting the rolling direction of the directional electrical steel sheet, the column spacing in the rolling direction of the electron beam irradiation is 2 to 10 mm, (E) of not less than 0.2 mm and not more than 1.0 mm and per unit beam diameter defined by the following formula (1) is not less than 30 mJ / mm and not more than 180 mJ / mm.

E = [electron beam acceleration voltage (kV) x beam current value (mA) x irradiation time (mu s) / 1000] / beam diameter (mm) (One)

4. When the thermal deformation is introduced by a continuous laser irradiation in a matrix in which strain points are arranged in a direction intersecting with the rolling direction of the directional electrical steel sheet, the interval of heat in the rolling direction of the continuous laser irradiation is 2 to 10 mm, Wherein a point interval is not less than 0.2 mm and not more than 1.0 mm and an amount of irradiation energy E per unit beam diameter defined by the following formula (2) is not less than 40 mJ / mm and not more than 200 mJ / mm.

E = [average laser power (W) x irradiation time (μs) / 1000] / beam diameter (mm) (2)

By imparting deformation to the scales under the regulation according to the present invention, any iron loss in the direction of rolling and rolling can be reduced. Therefore, in a transformer in which such a directional silicon steel sheet is laminated, the core loss can be made smaller.

1 is a graph showing the relationship between the distance between adjacent deformation areas and the iron loss.
2 is a graph showing the relationship between the spacing between adjacent deformation areas and the iron loss.
3 is a graph showing the relationship between the size of the deformation area and the iron loss.
4 is a graph showing the relationship between the size of the deformation area and the iron loss.
5 is a view showing the iron core shape of the transformer.

As described above, in order to reduce the iron loss in the transformer, it is necessary to lower the iron loss in both the rolling direction and the direction perpendicular to the rolling direction. First, in order to lower the iron loss in the rolling direction, it is important to form the thermal deformation region under the condition that the size of the deformation region is 0.10 mm or more and 0.50 mm or less and the interval between the adjacent deformation regions is 0.60 mm or less. On the other hand, in order to lower the iron loss in the direction perpendicular to the rolling direction, it is important to form the thermal deformation region under the condition that the size of the deformation region is 0.10 mm or more and the interval between adjacent deformation regions is 0.10 mm or more.

In addition, it is preferable that the interval of heat in the rolling direction of the deformation to be introduced on the ascending matrix is 2 mm or more and 10 mm or less. If the heat interval is less than 2 mm, the deformation introduction is too much, and the hysteresis loss in the rolling direction is greatly increased. On the other hand, if it exceeds 10 mm, the effect of refining the magnetic domain becomes smaller, and the iron loss in the rolling direction and the direction perpendicular to the rolling direction increases.

Further, it is preferable that the deformation to be introduced in an ascending order in the direction intersecting with the rolling direction of the steel sheet is such that the angle of the heat with the direction perpendicular to the rolling direction is within 30 degrees. When the inclination angle with respect to the direction perpendicular to the rolling direction is made larger than this range, the iron loss in the direction perpendicular to the rolling direction is reduced, but the amount of reduction of the iron loss in the rolling direction becomes smaller. More preferably, the deformation is introduced in the rolling orthogonal direction.

By satisfying the above-mentioned conditions, an appropriate amount of deformation is introduced into the steel sheet, reflux magnetic flux is generated, and the iron loss in the rolling direction and the direction perpendicular to the rolling direction are sufficiently reduced together to achieve reduction of iron loss in the transformer intended by the present invention Which is the optimum directional electric steel sheet. Outside this proper range, since the deformation amount is small and the effect of reducing the iron loss is small, or the amount of deformation is excessively large, or the deformation area is wide, the increase in the hysteresis loss increases and the iron loss reduction effect becomes small.

Next, a manufacturing method for introducing thermal deformation under the above conditions will be described.

First, electron beam irradiation or continuous laser irradiation capable of introducing a large energy at a converging beam diameter is suitable as an introduction method of the matrix strain. As another method of domain refinement, a technique by plasma jet irradiation is known, but it is difficult to be accommodated within the conditions of the present invention.

(i) Introduction of thermal deformation by electron beam irradiation

For the electron beam, experiments were carried out with various gap intervals and irradiation energy (E), and the irradiation conditions for introducing the thermal deformation described above were examined. Here, the irradiation energy amount E is defined by the following equation.

E (mJ / mm) = [electron beam acceleration voltage (kV) x beam current value (mA) x irradiation time (s) / 1000] / beam diameter (mm)

The beam diameter is defined by the known full-width at half maximum (FWHM) of the energy profile by a known slit method.

As a result of the above examination, it has been found that the heat interval in the rolling direction of the electron beam irradiation is 2 to 10 mm, the irradiation point interval in the line-in line is 0.2 mm or more and 1.0 mm or less, the irradiation energy amount E per unit beam diameter is not less than 30 mJ / / Mm or less, it was found that the deformation introduction condition described above was satisfied.

(ii) introduction of thermal deformation by continuous laser irradiation

Also, for the continuous laser irradiation, a range satisfying the above conditions was similarly investigated. Here, the irradiation energy amount E is defined by the following equation.

E (mJ / mm) = [average laser power (W) x irradiation time (mu s) / 1000] / beam diameter (mm)

As a result of the above examination, it has been found that the thermal spacing in the rolling direction of the laser irradiation is 2 to 10 mm, the irradiation point interval in the line-in line is 0.2 to 1.0 mm, the irradiation energy amount E per unit beam diameter is not less than 40 mJ / / Mm or less, it was found that the deformation introduction condition described above was satisfied.

Further, when the laser moves between the irradiation points, the laser emission may be turned off or a low output power may be used. The beam diameter is a value uniquely set from the collimator and the focal length of the lens in the optical system.

The method of introducing deformation into the matrix is repeated by rapidly stopping the electron beam or the laser beam at a predetermined time interval while scanning the electron beam or the laser beam for a time suitable for the present invention and continuing to irradiate the beam at that point, . In order to realize this process in the electron beam irradiation, the deflection voltage of the electron beam may be changed by using an amplifier having a large capacity.

Incidentally, if deformation is introduced by an electron beam or a continuous laser on an ascending matrix, irradiation marks may remain depending on the conditions, and the insulating properties of the steel sheet may be deteriorated. In that case, the insulating coating is subjected to a re-coating and baking is performed in a temperature region where the introduced deformation is not removed.

Next, production conditions of the grain-oriented electrical steel sheet other than the above will be described in detail. Further, the higher the degree of integration in the <100> direction of the crystal grain is, the greater the effect of reducing the iron loss due to the domain refining becomes. Therefore, the magnetic flux density B ₈ , which is an index of the degree of integration, is preferably 1.90 T or more.

In the present invention, the composition of the slab for a grain-oriented electrical steel sheet may be a constituent composition in which secondary recrystallization occurs. When an inhibitor is used, for example, Al and N may be used in the case of using an AlN inhibitor, and Mn and Se and / or S may be contained in an appropriate amount in the case of using an MnS MnSe system inhibitor. Of course, both inhibitors may be used in combination. The registered contents of Al, N, S and Se in this case are 0.01 to 0.065 mass% of Al, 0.005 to 0.012 mass% of N, 0.005 to 0.03 mass% of S and 0.005 to 0.03 mass% of Se, respectively .

The present invention is also applicable to a directional electric steel sheet in which the content of Al, N, S and Se is limited and no inhibitor is used. In this case, the amount of Al, N, S and Se is preferably controlled to be not more than 100 mass ppm of Al, not more than 50 mass ppm of N, not more than 50 mass ppm of S, and not more than 50 mass ppm of Se, respectively.

The basic components and optionally added components of the slab for a directional electric steel sheet of the present invention will be described in detail as follows.

C: not more than 0.08% by mass

C is added for the purpose of improving the hot rolled sheet structure. When it exceeds 0.08 mass%, the burden of reducing C to 50 mass ppm or less, which does not cause magnetic aging during the production process, increases. desirable. Regarding the lower limit, secondary recrystallization is possible even in a material containing no C, so that it is not necessary to form it particularly.

Si: 2.0 to 8.0 mass%

Si is an effective element for improving the iron loss by increasing the electrical resistance of the steel. When the Si content is 2.0% by mass or more, particularly, the iron loss reducing effect is good. On the other hand, when it is 8.0% by mass or less, particularly excellent processability and magnetic flux density can be obtained. Therefore, the amount of Si is preferably in the range of 2.0 to 8.0% by mass.

Mn: 0.005 to 1.0 mass%

Mn is a favorable element in favor of good hot workability, but if it is less than 0.005 mass%, the effect of addition is insufficient. On the other hand, when the content is 1.0% by mass or less, the magnetic flux density of the product plate becomes particularly good. Therefore, the amount of Mn is preferably in the range of 0.005 to 1.0% by mass.

In addition to the basic components described above, the following elements can be suitably contained as the magnetic property improving component.

0.001 to 1.50 mass% of Ni, 0.03 to 1.50 mass% of Ni, 0.001 to 1.50 mass% of Sb, 0.03 to 3.0 mass% of Cu, 0.03 to 0.50 mass% of P, 0.005 to 0.10 mass% of Mo, At least one selected from 0.03 to 1.50 mass%

Ni is a useful element because it further improves the hot rolled steel sheet structure and further improves the magnetic properties. However, when the content is less than 0.03 mass%, the effect of improving the magnetic properties is small. On the other hand, when the content is less than 1.5 mass%, the stability of the secondary recrystallization increases, and the magnetic properties are further improved. Therefore, the amount of Ni is preferably in the range of 0.03 to 1.5 mass%.

Sn, Sb, Cu, P, Cr, and Mo are each an element useful for improving the magnetic properties. However, if they are less than the lower limit of the above respective components, the effect of improving the magnetic properties is small. On the other hand, When the amount is less than the upper limit, the secondary recrystallization is most improved. For this reason, it is preferable that they are contained in the above respective ranges.

In addition, the remainder other than the above-mentioned components are inevitable impurities and Fe incorporated in the manufacturing process.

Subsequently, the slab having the above-mentioned composition is heated and hot-rolled by a conventional method, but may be hot-rolled immediately after casting without heating. In the case of thin strips, hot rolling may be performed, and the hot rolling may be omitted and the subsequent steps may be carried out.

Further, hot-rolled sheet annealing is carried out as necessary. The main purpose of the hot-rolled sheet annealing is to improve the magnetic properties by further improving the Goss structure in the secondary recrystallization annealing by eliminating the band structure generated in the hot rolling and making the primary recrystallization texture. At this time, in order to highly develop the goss structure in the product plate, the hot-rolled sheet annealing temperature is preferably in the range of 800 to 1100 ° C. If the annealing temperature of the hot-rolled sheet is less than 800 ° C, the band structure in the hot-rolling remains, and it becomes difficult to realize the established primary recrystallized structure and the desired secondary recrystallization can not be obtained. On the other hand, if the hot-rolled sheet annealing temperature exceeds 1100 ° C, the grain size after the hot-rolled sheet annealing becomes excessively coarse, and it becomes very difficult to realize the established primary recrystallized structure.

After the hot-rolled sheet annealing, cold rolling is performed twice or more while cold rolling or intermediate annealing is performed one time, then decarburization annealing (also used for recrystallization annealing) is performed, and an annealing separator is applied. After the annealing separator is applied, the final annealing is performed for the purpose of forming secondary recrystallization and a pole stellite coating (a coating mainly composed of Mg ₂ SiO ₄ ).

The annealing separator preferably contains MgO as a main component in order to form polysterite. Here, the main component of MgO means that a known annealing separator component other than MgO and a property improving component may be contained in the range that does not inhibit the formation of the intended antioxidant film of the present invention.

After final annealing, it is effective to perform planarization annealing to correct the shape. Further, in the present invention, an insulating coating is applied to the surface of the steel sheet before or after the planarization annealing. Here, this insulating coating means a coating capable of imparting a tensile force to the steel sheet (hereinafter referred to as tension coating) in order to reduce iron loss in the present invention. Examples of the tension coating include an inorganic coating containing silica, a ceramic coating by physical vapor deposition, chemical vapor deposition, and the like.

In the present invention, the directional electric steel sheet after the above-described final finishing annealing or tension coating is subjected to the domain refining by irradiating the surface of the steel sheet with an electron beam or a continuous laser under the above-described conditions.

In the present invention, a method of manufacturing a directional electrical steel sheet other than the above-described processes and manufacturing conditions may be applied to a known subdivision process using an electron beam or a continuous laser.

Example

A cold-rolled sheet rolled to a final plate thickness of 0.23 mm containing 3% by mass of Si was subjected to decarburization and primary recrystallization annealing, then an annealing separator containing MgO as a main component was applied, and a secondary recrystallization process and a refining process To obtain a directional electrical steel sheet having a polestellite coating. 60% colloidal silica and an aluminum phosphate coat were applied and baked at 800 ° C. Subsequently, an electron beam or a laser beam was radiated at a right angle to the rolling direction, and the deformation introduction was carried out in an ascending matrix or continuously. In the case of the focused irradiation, the interval in the direction perpendicular to the rolling direction was changed by controlling the stop time interval of the beam scanning. As a result, a material having a magnetic flux density B ₈ of 1.90 T to 1.94 T was obtained.

The thus obtained specimens were sheared into quadrangular shapes and dimensions as shown in Fig. 5, and were layered in an alternating lamination manner to form 70 layers, thereby fabricating a transformer having a length of 500 mm and a triangular shape shown in Fig. 5 . The power meter was used to measure no-load hand (transformer iron loss) at 1.7 T and 50 Hz excitation.

The measured iron loss of the transformer is summarized in Tables 2 and 3 together with the irradiation parameters, the size of the introduced strain region, and the interval between the adjacent strain regions.

As shown in Tables 2 and 3, in the case of a suitable example in which thermal deformation is introduced at a suitable deformation area size and an interval between adjacent deformation areas, both the electron beam irradiation and the continuous laser irradiation, Compared to the control group.

Claims (4)

A directional electrical steel sheet in which thermal deformation is introduced in a matrix in which strain points are arranged in a direction intersecting with the rolling direction only on one side of the steel sheet, characterized in that the size of the deformation area introduced from the above-mentioned matrix is 0.10 mm or more and 0.50 mm or less, Wherein the interval between the rows of the row and the row of the matrix is in the range of 0.10 mm to 0.60 mm and the row interval in the rolling direction is 2 to 10 mm. When introducing thermal deformation into a matrix of rows of strain points aligned in a direction crossing the rolling direction only on one side of the grain-oriented electrical steel sheet, the column spacing in the rolling direction of the electron beam irradiation is 2 to 10 mm, The irradiation energy amount E per unit beam diameter defined by the following formula (1) is not less than 30 mJ / mm and not more than 180 mJ / mm,
Wherein a size of the deformation area introduced from the matrix is 0.10 mm or more and 0.50 mm or less and a distance between adjacent deformation areas is 0.10 mm or more and 0.60 mm or less.
E = [electron beam acceleration voltage (kV) x beam current value (mA) x irradiation time (mu s) / 1000] / beam diameter (mm) (One) When the thermal deformation is introduced by a continuous laser irradiation in a row in which strain points are arranged in a direction intersecting the rolling direction only on one side of the directional electrical steel sheet, the row interval in the rolling direction of the continuous laser irradiation is 2 to 10 mm, The irradiated energy amount E per unit beam diameter defined by the following formula (2) is not less than 40 mJ / mm and not more than 200 mJ / mm,
Wherein a size of the deformation area introduced from the matrix is 0.10 mm or more and 0.50 mm or less and a distance between adjacent deformation areas is 0.10 mm or more and 0.60 mm or less.
E = [average laser power (W) x irradiation time (μs) / 1000] / beam diameter (mm) (2) delete

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